WebMD reports that, according to expets from the CDC and FDA, more than 700,000 people visit U.S. emergency rooms each year due to adverse drug reactions, including allergic reactions to drugs and accidental overdoses. People over 65 are most at risk.

Most patients were released soon after treatment, but roughly 117,000 patients required hospitalization. The cases of hospitalization most often involved drugs that require monitoring to avoid toxic build-up. The five most common classes of drugs that caused adverse drug reactions are:

Antihistamines & Cold Remedies

Painkillers containing Opioids

Anticlotting Drugs

Amoxicillin

Insulin

The key to avoiding adverse drug reactions is to avoid the drugs that may cause them (whenever possible, of course). In the case of allergies, if you avoid the allergens that make you sick, then you won't need to take as many drugs to relieve your symptoms.